export default {
  // 为当前模式开启命名空间
  namespaced: true,
  
  // 模块的 state 数据
  state:() => ({
    // 购物车的数组，用来存储购物车中每个商品的信息对象
    // 每个商品的信息对象，都包含如下 6 个属性
    // { goods_id, goods_name, goods_price, goods_count, goods_small_logo, goods_state }
    cart: uni.getStorageSync('cart') ? JSON.parse(uni.getStorageSync('cart') || []) : []
    // cart: uni.getStorageSync('cart') || []
  }),
  
  // 模块的 mutions 方法
  mutations: {
    // 添加数据
    addToCart(state,goods){
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      if (!findResult) {
        state.cart.push(goods)
      }else {
        findResult.goods_count++
      }
      
      // 通过 commit 方法调用 m_cart 命名空间下的 saveToStorage
      this.commit('m_cart/saveToStorage')
    },
    // 数据持久化
    saveToStorage(state){
      uni.setStorageSync('cart', JSON.stringify(state.cart))
    },
    // 更改选中状态
    radioChange(state,goods){
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      if (findResult) {
        findResult.goods_state =goods.goods_state
        this.commit('m_cart/saveToStorage')
      }
    },
    // 更改所有商品选中状态
    updateAllGoodsState(state,newState){
      state.cart.forEach(x => x.goods_state = newState)
      this.commit('m_cart/saveToStorage')
    },
    // 更改商品数量
    numberChange(state,goods) {
      const findResult = state.cart.find(x => x.goods_id === goods.goods_id)
      if (findResult) {
        findResult.goods_count =goods.goods_count
        this.commit('m_cart/saveToStorage')
      }
    },
    // 根据 id 删除商品
    removeGoodsById(state,goods){
      state.cart = state.cart.filter(x => x.goods_id !== goods.goods_id)
      this.commit('m_cart/saveToStorage')
    }
  },
  
  // 模块的 getters 属性
  getters: {
    // 计算商品总数量
    total(state){
      // let c = 0
      // state.cart.forEach(x => c += x.goods_count)
      // return c
      return state.cart.reduce((total,item) => total += item.goods_count,0)
    },
    // 计算勾选商品的总数量
    checkedCount(state){
      return state.cart.filter(x => x.goods_state).reduce((total,item) => total += item.goods_count ,0)
    },
    // 计算勾选商品的总价格
    checkedPriceCount(state){
      return state.cart.filter(x => x.goods_state).reduce((total,item) => total += item.goods_count*item.goods_price,0).toFixed(2)
    }
  }
}